Welcome aboard Mike.
Plenty of co2 1911s available in the U.K.
Oddly airsoft replicas are only available to shooters who register as airsoft players or have another 'defence' allowing them to buy a replica.
In other words Adults can only buy the more powerful ones as they are classed as airguns and not replicas.
And airguns are classed as firearms over here but legal to own without licence if under certain power limits.
You will get used to our odd Firearms Laws if you spend time on here!